Publications

The well target was originally planned to be drilled from a new well slot, but a reassessment concluded to use an existing well slot for re-drill option as an optimization for cost and for planned well trajectory. The 9-5/8” whipstock system with integral Tri-mill BHA was selected for optimum milling operation for dual casing window (9-5/8” x 13-3/8”). TOC data behind 13-3/8” casing was not available while the CBL/VDL log result on 9-5/8” casing performed prior to rig move-in was inconclusive. Whipstock was then ran and set at planned depth, fluid in hole displaced to SBM, and milling the casing window proceeded. Pressure increase was observed in annulus 95/8” x 13-3/8” casing during milling due to poor cement isolation behind the 9-5/8” casing and potentially leading to well integrity issues for drilling the next section. After completing the milling operation and drilling out new formation, FIT was performed as per program before pulling out milling BHA. Remedial cement casing was then carried out with reversed mode thru 13-3/8” casing valve by manipulating the surface choke to avoid any cement falling around the existing casing window. The dual casing window was successfully made with single trip. The sequenced drilling BHA could pass thru the casing window without any issue and remedial reverse cementing also gave proper isolation capability in casing annulus to allow drilling for the next hole section.